1. Field of the Invention
The invention relates to a bio-microarray having probe biomolecules such as DNA, peptide, protein, polysaccharide, cell, and tissue, which are arranged in an array, and also relates to a substrate for bio-microarray.
2. Description of the Related Art
In recent years, the target of development of bio-microarrays (also referred to as biochips) has been expanded and thus includes not only DNA microarrays, which have been used in genome analysis, but also microarrays that load any other biomolecules such as peptide, protein, polysaccharide, cell, and tissue.
The bio-microarray analysis method generally includes the processes of introducing a fluorescent molecule as a label into a sample and analyzing light emission from the fluorescent molecule, because such a process is appreciated as having a high sensitivity and a variety of available labels. Examples of the analytical apparatus according to this method include: a high accuracy type apparatus that uses the principle of confocal microscope and performs a spot-by-spot analysis on the bio-microarray; and a high throughput type apparatus that uses a charge-coupled device array or the like as a detector and analyzes a plurality of spots in a specific region at a time. In this method, for example, the data signal-to-noise ratio can be reduced by such a factor as a noise generated at the time of data amplification/conversion, the reflection of excitation light (incident light), dust on the substrate, an unevenness in the surface treatment state of a glass substrate, and a background fluorescence. In particular, the reflection of excitation light is a remarkable cause of the reduction inaccuracy that can come from the substrate.
On the other hand, an increase in the detected signal intensity requires sufficient absorption of the excitation light into the label of the fluorescent molecule, and therefore, in some cases, suppression of the reflection of the excitation light can reduce the analysis accuracy depending on the intensity of the excitation light.
Thus, it is desirable that the user should use different substrates so that the reflection of excitation light can be reduced or increased depending on the intensity of the excitation light. Specifically, however, substrates produced with no optical processing and substrates having the function of increasing the reflection are only commercially available now. In some cases, such substrates cannot provide sufficient analytical accuracy, depending on the intensity of the excitation light.